Abstract. An altered gingival inflammatory response to supragingival plaque in smokers had been claimed by several authors. Relatively limited information exists with regard to the consistency of naturally occurring plaque and bleeding upon probing within the oral cavity under usual oral hygiene measures. The aims of the present study were to describe the distribution of tooth surfaces covered by supragingival plaque and gingival units bleeding upon probing in a steady state environment of no dental intervention. In addition relative consistency of plaque and bleeding was investigated. 65 volunteers, 14 women and 51 men in the age range of 19 to 30 years, participated. 33 volunteers were heavy smokers and 32 non-smokers. Clinical examinations revealed mild, plaque-induced gingivitis with no overt destructive periodontitis. Within a 6-month period, presence and amount of plaque, calculus and gingival bleeding was site-specifically assessed four times, i.e., every 8 weeks. Well-defined, symmetric and consistent patterns of plaque and calculus distribution within the oral cavity were observed, which were rather identical in smokers and non-smokers. Smokers had evenly more plaque in all regions of the oral cavity. In contrast, there was no obvious pattern of bleeding upon probing. Consistency of observations was considerably lower than for plaque scores. This was particularly true for smokers, where the association between bleeding scores was generally smaller than in non-smokers. A large portion of the variation of gingival bleeding may be due to presently unknown factors other than plaque and calculus with considerable consequences for preventive programmes.